Preface
This book is an outgrowth of teaching the heat transfer course over 25 years (CB) and over a decade of teaching (BS|SG). Additionally, during the past 4 years, the three of us have co-taught the undergraduate heat transfer course at the Indian Institute of Technology Madras, India in close coordination, with shared tutorials, assignments, and exams. It is our hope that, in view of the above, the readers do not find any jerk in the narration and presentation of core ideas of heat transfer, and in the mathematical treatment peppered with insightful physics. The nuances of the underlying physics are usually easy to miss and we have earnestly strived to get these across to the students, all through the book.
Heat transfer is not only a major engineering tool in the hands of a mechanical, chemical, aerospace, automotive, materials and electrical engineer, but is a discipline by itself, with its principles and techniques finding direct use in power generation, heating, ventilation, air conditioning, insulation systems, apart from applications in critical technologies, such as electronic cooling, combustion and propulsion, satellite cooling, data center cooling, heat removal from nuclear fuel rods in nuclear power plants, and so on. The list is endless. Heat transfer has witnessed spectacular growth in the last 100 years with accelerated development since World War II and has come out of the shadows of being an “inferior” interaction at a system boundary compared to work, as traditionally studied, taught and prescribed in an equally game-changing and fascinating subject of thermodynamics.
Even so, heat transfer has grown to be an independent discipline with numerous applications, where the primary objective (unlike in thermodynamics) is not the conversion of heat to work. Many applications, as already mentioned, demand a knowledge of the heat transfer physics, the rate and the means to increase or decrease the heat transfer rate as the case may be, along with an equally important engineering objective of keeping temperatures under check, across equipment in multifarious engineering disciplines.
In this book, we have endeavored to give a fresh flavor to heat transfer, always trying to keep the above objectives right through the text. The exposition in every chapter is aimed at an end-to-end experience, starting from the physics of the process to the engineering of the equipment that accomplishes the heat transfer. The two cardinal pillars we have strictly adhered to are (1) Fundamentals and (2) Techniques, as reflected in the title of the book.
The book is divided into 12 chapters. Chapter 1 deals with an introduction to the field of heat transfer and lists the possible applications of the subject. In Chapters 2 and 3, we elaborately present conduction heat transfer in several engineering systems, covering both steady and unsteady heat transfer. In Chapter 4, we present the basic ideas of convection and derive the equations governing the flow and the heat transfer. Chapter 5 provides an exhaustive treatment of forced convection involving both external and internal flow and also presents a quick introduction to turbulence.
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Prandtl’s legendary boundary-layer simplifications and the integral solution to the problem of convection heat transfer are elucidated. The powerful Reynolds analogy is presented together with a brief presentation of forced convection in other geometries of interest. In so far as internal flow is concerned, the concept of fully developed flow is elaborated, followed by a treatment of the analytical approach to getting the Nusselt number for a constant heat flux case. Correlations for turbulent flow and heat transfer are given for a few cases of engineering interest.
Chapter 6 discuses free convection in detail. Boundary layer simplifications, integral solutions, and correlations are presented for a few representative geometries.
Chapter 7 deals with the analysis and design of heat exchangers. Two powerful techniques, namely the logarithmic mean temperature difference and the effective- ness-number of transfer units (NTU), are detailed and specific instances of using one method over the other in an engineering problem are driven home through examples. Ideas on the overall heat transfer coefficient are reinforced in this chapter.
Chapter 8 presents an overview of basic radiation laws, black body behavior, and characteristics of real surfaces from the viewpoint of radiation. The enclosure theory is elaborately presented together with a detailed treatment of view factors to enable the calculation of radiation heat transfer between surfaces that are separated by a transparent medium. The chapter also gives a breezy introduction to gas radiation and its engineering treatment.
Chapter 9 provides an introduction to numerical heat transfer. There is a detailed discussion of the finite difference method for heat transfer, along with applications to problems handled analytically in earlier chapters. The chapter also discusses the need and indispensability of numerical methods for engineering heat transfer and the practical issues that a heat transfer engineer must consider in industrial problems.
Chapter 10 presents an introduction to applications of machine learning in heat transfer. We discuss the relevance and importance of this topic in modern day heat transfer and provide an overview of various machine learning algorithms in the context of possible applications in heat transfer. An elaboration of the learning process and neural networks is provided. Possible future applications of this topic are also given at the end of this chapter.
Chapter 11 presents the commonly observed regimes of pool boiling and flow patterns in flow boiling and the correlations used to predict the heat transfer coefficients and the critical heat flux. The wall superheat required for nucleation from a heating surface is briefly discussed. The theory of film condensation on flat plates and horizontal tubes is presented, along with the respective heat transfer coefficient correlations. An introduction to the prediction of two-phase pressure drop is also given.
Chapter 12 discusses the laws that govern diffusion and convective mass transfer, and the analogy between mass transfer and heat transfer. Equations for the determination of mass transfer coefficients for a gas flow over a volatile liquid or solid surface are presented.
It is our trust and hope that the material presented in the book, together with the worked examples and the end of chapter problems, will be more than adequate for
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coverage in a one-semester course either at the third-year undergraduate level or at the first-year Masters level. For the undergraduate course, instructors may at their discretion, not dwell too much on advanced topics like gas radiation or machine learning. Even so, these are important, and the decision is best left to the instructor/ reader.
We would like to thank IIT Madras for providing us with an academically stimulating environment to teach, practice, and research the ever-glorious subject of heat transfer. Thanks are due to all our teachers who have been a key source of motivation and to thousands of students over the years; who have often surprised and humbled us with matter-of-fact yet deep questions that have quite a few times left us startled and speechless.
To all at Elsevier starting from Gaelle Hull, Publisher, Thermal and Fluids Engineering to Nisbet Graham, Senior Acquisitions Editor, Energy, Mona Zahir, Editorial Project Manager and Poulouse Joseph, Senior Project Manager, for making this happen and for the relentless follow-up and back by Poulouse and Mona.
We are extremely grateful to our scholars, Girish, Rajesh, Sandeep, Sangamesh, Suraj, Harish, Kiran, Vikas Dwivedi, Gaurav Yadav, Rishi Mishra, Akhil Dass and Prasanna Jayaramu, for their help in typing, preparation of figures, and proof corrections. They have been pillars of support to us in the entire project.
Finally, we are ever grateful to our families for their support, encouragement, and forbearance.
Chennai, India |
C. Balaji |
August 2020 |
Balaji Srinivasan |
|
Sateesh Gedupudi |